8006

• UCREFRP Catalog Number: 8006
• Author: Hawkins, J. A., E. J. Wick and D. E. Jennings.
• Title: Icthyofauna of the Little Snake River, Colorado, 1994 - Final Report.
• USFW Year: 1997.
• USFW - Doc Type: Denver, CO.
• Copyright Material: NO

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baseflow on June 17-19 and July 11-15. On October 21-24, a few additional
seine samples were taken while we assisted with a channel monitoring study.
Sample gear and methods targeted both large and small fish and varied depending
on river access, discharge, habitat, and safety. Small fish were collected with
small seine, dipnet, and castnet and large fish with large seine, angling gear,
electrofishing boat, backpack-electroshocker, bank-electrofisher, gill net, and
trammel net (Appendix Table A.1). Trammel and gill nets were set in eddies along
the eddy-run interface and fish were removed from nets every 30 minutes to
reduce their stress. Angling gear included worms, crickets, dry-flies, and spoon-
type lures with barbless hooks. Seine and dipnet gear were used to sample near-
shore and backwater habitats and a cast net was used to sample large, shallow
pools that were difficult to seine.

All fish were measured for maximum total length (Anderson and Gutreuter
1983) and those over 100 mm were cradled in a net and weighed with Homs or
Chatillon brand spring scales (Jennings 1989). All fish were released alive after
measurements unless fish identification was uncertain, then fish were
anaesthetized and overdosed with tricaine (trade name Finquel@) and preserved in
10% formalin for laboratory identification. Preserved specimens were later
transferred to 3% buffered formalin, identified, and cataloged at the Larval Fish
Laboratory, Colorado State University.

For data analysis, fish were segregated into life stages based on
morphological development (Snyder 1981; Snyder and Muth 1990). Life stages
included larva, juvenile, and adult; size at each stage varied by species (Table 1).
For additional clarity, species were grouped into large-bodied or small-bodied forms
based on the approximate length at which they become adults. Large-bodied
species were considered adults at 2..200 mm and small-bodied species were
considered adults at < 200 mm (Table 1). Spawning period was estimated for
each species based on when adult fish expressed sperm or eggs or had secondary

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